Current-voltage characteristics of graphene devices: Interplay between Zener-Klein tunneling and defects

Abstract

We report a theoretical/experimental study of current-voltage characteristics $(I\text{\ensuremath{-}}V)$ of graphene devices near the Dirac point. The $I\text{\ensuremath{-}}V$ can be described by a power law ($I\ensuremath{\propto}{V}^{\ensuremath{\alpha}}$ with $1<\ensuremath{\alpha}\ensuremath{\le}1.5$). The exponent is higher when the mobility is lower. This superlinear $I\text{\ensuremath{-}}V$ is interpreted in terms of the interplay between Zener-Klein transport, that is tunneling between different energy bands, and defect scattering. Surprisingly, the Zener-Klein tunneling is made visible by the presence of defects.